While I certainly agree with the sentiment, it really doesn't take very much "out of sight" time for this stuff. 10 minutes, summer clothing, baby 9 months later. I know from experience that if I ever had a daughter, she won't ever, ever, not once, not EVER, be out of sight with a hormonally charged teenage male.
I agree, I'd do the same if I had a daughter. But remember, it's not just the boys fault. Girls like sex just the same as guys, they're not all innocent victims either.